The invention relates generally to electrical connectors and, more particularly, to a connector assembly having features for inhibiting electromagnetic emissions.
Electromagnetic interference (EMI) is commonly encountered in the operation of electronic systems. EMI can cause electronic equipment to malfunction when the equipment is not sufficiently shielded. EMI becomes more problematic as processing speeds increase. Some electronic devices may be mounted on or adjacent to a panel inside a chassis or cabinet. In the cabinet, doors and seams are sources for the escape of radiation or electromagnetic energy from the cabinet that may cause electromagnetic interference. The leak or escape of radiation from the cabinet may be monitored and may be subject to FCC regulation.
Compressive gaskets are commonly applied around connections between electrical components to suppress EMI. In addition to being compressible, the gasket is intended to provide conductivity to ensure electrical continuity between mating surfaces of the components. However, tolerances associated with the positioning of connectors on the panel require that the gasket have a deflection range sufficient to effectively seal against EMI leakage between the connector and the panel. Some known gaskets are made from a conductive elastomer, which is inserted into a channel between two mating surfaces. In addition, the gasket may be glued to the inside of the channel. In such arrangements, the channel is used to provide lateral stability for the gasket and to prevent misalignment that could result over time from the repeated separation of the components. In another known shielding method, a compressible gasket is formed from a conductive metal and attached to a metal band along its length. The metal band is sandwiched between the mating surfaces of the components when the components are mated.
With the ongoing trend toward the development of smaller components, such as the newer secure digital (SD) memory card form factor, less space or structure is available on the connectors for features such as EMI suppression. SD memory card connectors are typically designed with a conductive shield and may have grounding tabs or pads that may be connected to a ground plane on a circuit board. However, a space may still be present between the connector and a panel which may allow EMI radiation or energy to escape from the cabinet. For instance, the panel may be a chassis or cabinet wall that is integral with the chassis bottom or floor, usually with a right angle bend. There are angular tolerances associated with the bend. The connector may be mounted on a circuit board that is aligned with standoffs on the chassis floor. There are tolerances associated with the location of the standoffs on the chassis floor as well as the position of the circuit board on the standoffs and the connector on the circuit board. As a result, there is a tolerance accumulation between an edge of the circuit board and the panel that produces a space between the connector and the panel through which EMI emissions may escape from the chassis. Thus, the effective suppression of electromagnetic emissions remains a challenge.